You could use cheap distilled water, or rainwater. Most tap water is basic, Acidic water eats pipes, cities add carbonates to make it basic. I have a large demand for acidic water. I grow blueberries which have to be kept acidic. I use sulfuric acid in rainwater. You will not need Captan if gray mold is not a problem, but also helps with leaf spot! 4 to 8 tbs per gallon. Use at least 6, These are label directions. You can view label here http://www.bonide.com/lbonide/backlabels/l171.pdf Spray till plant is soaking wet dripping, and try to get underneath leaves. Some plants can be damaged by too much captan, but I have never seen this with strawberries. So use best judgement, do not overdo it, but spray very well! The use of acidic water is not documented, but growers have told me this, and I believe it. 2 years ago I was complaining about captan not working. I was still getting gray mold. I was told about the acidic water. i tried it this year and no gray mold. It most certainly worked!

I'm late to this but I thought I'd add some advice. I have a small grove of about 24 trees (Hass, Fuerte and Zutano) in Southern California. Leaf tips turning brown is usually a sign of water problems. When the soil dries out, it leaches salt from the ground (which is bad) and causes the tip burn. If you have spots on the leaves, that's usually a pest like a persea mite. My trees are in Sandy Loam soil. You can tell if they need water by clumping the soil in your hand. If it drips water when you squeeze it, it's too wet. Soil that is too wet will lead to root rot. If it doesn't hold a shape from your fingers when you squeeze it, it's too dry and they'll leach salts from the ground. It should hold the shape from your fingers. They like a lot of water but they don't like sitting in water. It has to drain away. That's why most avocado groves are on hillsides. If you don't have hilly land, build a mound and plant the tree in the middle of it so the water can drain off. They like full sun but they have to be protected from sunburn when they're young if it gets really hot where you are. If the trunk or branches are turning black, they may be getting sunburned. To protect it, mix 1/2 white indoor latex paint and 1/2 water (whitewash) and paint the trunk and any exposed branches with it. Once you get a nice canopy, you can stop painting the trunk. Usually once per year is all that is necessary. Don't let the canopy touch the ground. Keep the canopy trimmed about 2 feet off the ground. My trees usually get two waterings per week in the summer when it's hot and sunny, one short and one long. If I get rain of 1/2" or more, I don't water for about a week. In the winter, when it rains here, I may not need to water at all. They usually don't like pots either. Their roots are shallow and spread out to the canopy of the tree. They can tolerate cold down to about 27F. If you get frost or snow, it will kill the tree. They also like a soil ph of 6 to 6.5. It's normal for leaves to fall in the winter. Leave them around the tree and don't let grass or weeds near them. Resist the temptation to clean up the leaves. They help protect the roots and help keep the soil from drying out too quickly. The licorice smell from a torn leaf is usually the sign of a tree that won't grow avocados. It should have a fresh green smell. Growing from a pit will usually not produce avocados and if it does, it's going to take about 10 to 15 years to produce, and even then, they may not produce good tasting fruit. Most growers buy grafted trees or graft themselves from a verified tree that produces good fruit.

Thanks for the input. There doesn't appear to be a fungus so I'll just let it do its thing. We did go through a similar weather pattern, ken_adrian. (btw, are you in Adrian? I went to U of M). It sounds like buckeyes are temperamental (insert Michigan/Ohio State joke here) and I guess I'm lucky to just now have issues. Honestly, I wouldn't have even noticed except the darn thing is making a mess of my pool and deck!

Since two are not showing the brown edges and tips, I would guess that the root ball of the third has dried out and cannot absorb moisture like the others. Carefully scrape away the soil and give the root ball the finger test. If it is dry, dig up the plant, distress the roots if they are matted and soak it in water for a half hour, then replant. This procedure will not harm the rhododendron. Water as needed with just a trickle from a hose at the base of the plant until the ground freezes. rhodyman's advice to check the soil pH is well worth following. I am - really guessing with this one - thinking, though, that the leaves look fine and the flowers are yellow. About the only two varieties of yellow rhododendrons I can think of likely to do well ( or at least well enough to be sold there) in MI (Zone 5?) are Capistrano and Lemon Dream. Both have the species wardii in their backgrounds and are very susceptible to root fungus diseases. You need to be careful about overwatering, especially in hot weather and both need excellent drainage. Planting in pure conifer bark with the root ball slightly above grade can help.